Comparative Study on Growth and Disease Resistance of Hybrids between Chinese and Korean Stocks of Sea Cucumber Apostichopus japonicus

Abstract:

The sea cucumber Apostichopus japonicus is a major aquaculture species in China. The fast development of sea cucumber culture in China has generated some problems such as genetic degradation, frequent diseases outbreak and natural resource depletion, which have impacted the sustainable develop­ment of agro industry of sea cucumber. Heterosis resulting from crosses between different populations is an important component of breed improvement in marine animals. The objective of this study is to determine if heterosis exists between China and Korea populations of A. japonicus. The first generation of four combinations, C(♀)×C(♂), K(♀)×K(♂), K(♀)×C(♂), and C(♀)×K(♂), were obtained from mating and crossing within and between Chinese population (C) and Korean population (K) of A. japonicas. The fertilization rate, hatch rate, settlement rate, growth, disease resistance and heterosis at larval and juvenile stages were compared among four combinations in this study. The results indicated that fertilization and hatch rates were not significantly different between the hybridization groups and self-fertilized groups. The settlement rates of hybridization groups were significantly higher than those of self-fertilized groups (P<0.05). The body length of C(♀)×K(♂) group at juvenile stages was longer than other three groups, showing marked heterosis 9.43%–23.75%. Compared with other three groups, heterosis on body weight of C(♀)×K(♂) group ranged from 4.09% to 34.96% since 150 days after fertilization. In contrast, the K(♀)×C(♂) group did not show positive heterosis except at Day 150. The K(♀)×C(♂) group showed the best resistance against V. splendidus, and the heterosis reached 26.21%. These results indicated that the crosses between different populations might be effective for genetic improvement in A. japonicus.